1. Field of the Invention
The present invention relates to a display device.
2. Description of the Related Art
A display device having a touch panel as an interface has been known (JP 2008-83491 A). Among a variety of the touch panels, a capacitance touch panel has been extensively used for a smart phone or the like since the panel operates smoothly only by touching it with a fingertip. The display panel is configured such that a display panel laps over the touch panel.
The display panel is formed with a large number of signal lines that supplies image signals for forming an image, and an electromagnetic wave noise is developed by the image signals. Because the capacitance touch panel needs to detect a slight change in the capacitance, the surrounding noise adversely affects a position detection precision.
As a result of the analysis by the present inventors, it is found that a coupling capacitance is formed between a common electrode set to a reference potential and the signal lines, and a potential of the common electrode is varied according to the image signals that pass through the signal lines. An electromagnetic wave noise is also generated in the common electrode due to the variation in the potential in addition to the electromagnetic wave noise from the signal lines, resulting in a possibility that the capacitance touch panel malfunctions.